The analyses revealed relationships between the species and genome groups and showed a generally high level of intraspecific genetic diversity. The improved knowledge of species relationships should facilitate the utilization of wild species for peanut improvement. The estimates of speciation rates in section Arachis are high, but not unprecedented. We suggest these high rates may be linked to the peculiar reproductive biology of Arachis.

Modern genotyping techniques, such as SNP analysis and genotyping by sequencing (GBS), are hampered by poor DNA quality and purity, particularly in challenging plant species, rich in secondary metabolites. We therefore investigated the utility of a pre-wash step using a buffered sorbitol solution, prior to DNA extraction using a high salt CTAB extraction protocol, in a high throughput or miniprep setting. This pre-wash appears to remove interfering metabolites, such as polyphenols and polysaccharides, from tissue macerates. We also investigated the adaptability of the sorbitol pre-wash for RNA extraction using a lithium chloride-based protocol. The method was successfully applied to a variety of tissues, including leaf, cambium and fruit of diverse plant species including annual crops, forest and fruit trees, herbarium leaf material and lyophilized fungal mycelium. We consistently obtained good yields of high purity DNA or RNA in all species tested. The protocol has been validated for thousands of DNA samples by generating high data quality in dense SNP arrays. DNA extracted from Eucalyptus spp. leaf and cambium as well as mycelium from Trichoderma spp. was readily digested with restriction enzymes and performed consistently in AFLP assays. Scaled-up DNA extractions were also suitable for long read sequencing. Successful RNA quality control and good RNA-Seq data for Eucalyptus and cashew confirms the effectiveness of the sorbitol buffer pre-wash for high quality RNA extraction.

In 1991, the poinsettia strain, silverleaf whitefly or B biotype of Bemisia tabaci was detected in Brazil. This variant is a far more serious agricultural pest than the previously prevalent non-B (BR) biotype. The correct identification of B. tabaci is problematic since it is highly polymorphic with extreme plasticity in key morphological characters that vary according to the host. RAPD-PCR was used to survey the B biotype and other biotypes of B. tabaci in Brazil. Whiteflies were collected from cultivated plants and weeds from 57 different localities and on 27 distinct crops. RAPD analyses using two selected 10-mer primers reliably identified the BR biotype and the B biotype of B. tabaci and also differentiated other whitefly species. The presence of the B biotype was confirmed in 20 Brazilian states. The BR and B biotypes of B. tabaci were found to coexist in the whitefly populations of three different localities: Jaboticabal, SP; Rondonópolis and Cuiabá, MT, and Goiânia, GO.

Biological control of seed-borne pathogens has shown to enhance germination and physiological quality of seeds. The objectives of this study were to evaluate the in vitro antagonistic effect of five Trichoderma harzianum isolates (CEN287, CEN288, CEN289, CEN290, and CEN316) against Fusarium oxysporum f. sp. phaseoli (Foxy) and test its potential use in seed treatment. Initially, pathogen and antagonists were grown in paired cultures at 25ºC, from which samples were assessed using scanning electron microscopy (SEM). Then, clean or Foxy-infected seeds were treated with conidial suspension of the antagonists. Percent of Foxy-infected seeds and normal seedlings were evaluated at seven and nine days of incubation, respectively. All but one Trichoderma isolate (CEN290) inhibited Foxy mycelial growth. SEM analysis revealed that only one Trichoderma isolate (CEN287) showed parasitic interaction with Foxy. Two isolates (CEN287 and CEN316) significantly reduced the Foxy incidence and enhanced seed germination, though less effective than the fungicide mixture (carboxin + thiram). A principal component analysis indicated the importance of volatile metabolites in reducing Foxy incidence on common bean seeds. CEN287 Trichoderma harzianum isolate formed a single group due to its increase in germination rate of Foxyinfected seeds.

A phylogenetic analysis of the 5.8S rDNA and internal transcribed spacer (ITS1 and ITS2) sequences from some entomogenous Paecilomyces species supports the polyphyly of the genus and showed the existence of cryptic species. In the Eurotiales, anamorphs Paecilomyces variotii and Paecilomyces leycettanus were related to the teleomorphs Talaromyces and Thermoascus. In the Hypocreales, three major ITS subgroups were found, one of which included Paecilomyces viridis, Paecilomyces penicillatus, Paecilomyces carneus and isolates identified as Paecilomyces lilacinus and Paecilomyces marquandii. However, the majority of the P. lilacinus and P. marquandii isolates formed a distinct and distantly related subgroup, while the other major subgroup contained Paecilomyces farinosus, Paecilomyces amoeneroseus, Paecilomyces fumosoroseus and Paecilomyces tenuipes.